[PATCH 4/5] Add pg_xlogdump contrib module

From: Andres Freund <andres@anarazel.de>

Authors: Andres Freund, Heikki Linnakangas
---contrib/Makefile                  |   1 +contrib/pg_xlogdump/Makefile      |  37 +++contrib/pg_xlogdump/compat.c
|  58 ++++contrib/pg_xlogdump/pg_xlogdump.c | 654 ++++++++++++++++++++++++++++++++++++++contrib/pg_xlogdump/tables.c
 |  78 +++++doc/src/sgml/ref/allfiles.sgml    |   1 +doc/src/sgml/ref/pg_xlogdump.sgml |  76
+++++doc/src/sgml/reference.sgml      |   1 +src/backend/access/transam/rmgr.c |   1 +src/backend/catalog/catalog.c
|  2 +src/tools/msvc/Mkvcbuild.pm       |  16 +-11 files changed, 924 insertions(+), 1 deletion(-)create mode 100644
contrib/pg_xlogdump/Makefilecreatemode 100644 contrib/pg_xlogdump/compat.ccreate mode 100644
contrib/pg_xlogdump/pg_xlogdump.ccreatemode 100644 contrib/pg_xlogdump/tables.ccreate mode 100644
doc/src/sgml/ref/pg_xlogdump.sgml

diff --git a/contrib/Makefile b/contrib/Makefile
index fcd7c1e..5d290b8 100644
--- a/contrib/Makefile
+++ b/contrib/Makefile
@@ -39,6 +39,7 @@ SUBDIRS = \        pg_trgm        \        pg_upgrade    \        pg_upgrade_support \
+        pg_xlogdump    \        pgbench        \        pgcrypto    \        pgrowlocks    \
diff --git a/contrib/pg_xlogdump/Makefile b/contrib/pg_xlogdump/Makefile
new file mode 100644
index 0000000..1adef35
--- /dev/null
+++ b/contrib/pg_xlogdump/Makefile
@@ -0,0 +1,37 @@
+# contrib/pg_xlogdump/Makefile
+
+PGFILEDESC = "pg_xlogdump"
+PGAPPICON=win32
+
+PROGRAM = pg_xlogdump
+OBJS =  pg_xlogdump.o compat.o tables.o xlogreader.o $(RMGRDESCOBJS) \
+    $(WIN32RES)
+
+# XXX: Perhaps this should be done by a wildcard rule so that you don't need
+# to remember to add new rmgrdesc files to this list.
+RMGRDESCSOURCES = clogdesc.c dbasedesc.c gindesc.c gistdesc.c hashdesc.c \
+    heapdesc.c mxactdesc.c nbtdesc.c relmapdesc.c seqdesc.c smgrdesc.c \
+    spgdesc.c standbydesc.c tblspcdesc.c xactdesc.c xlogdesc.c
+
+RMGRDESCOBJS = $(patsubst %.c,%.o,$(RMGRDESCSOURCES))
+
+EXTRA_CLEAN = $(RMGRDESCSOURCES) xlogreader.c
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = contrib/pg_xlogdump
+top_builddir = ../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
+
+override CPPFLAGS := -DFRONTEND $(CPPFLAGS)
+
+xlogreader.c: % : $(top_srcdir)/src/backend/access/transam/%
+    rm -f $@ && $(LN_S) $< .
+
+$(RMGRDESCSOURCES): % : $(top_srcdir)/src/backend/access/rmgrdesc/%
+    rm -f $@ && $(LN_S) $< .
diff --git a/contrib/pg_xlogdump/compat.c b/contrib/pg_xlogdump/compat.c
new file mode 100644
index 0000000..e150afb
--- /dev/null
+++ b/contrib/pg_xlogdump/compat.c
@@ -0,0 +1,58 @@
+/*-------------------------------------------------------------------------
+ *
+ * compat.c
+ *        Reimplementations of various backend functions.
+ *
+ * Portions Copyright (c) 2012, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *        contrib/pg_xlogdump/compat.c
+ *
+ * This file contains client-side implementations for various backend
+ * functions that the rm_desc functions in *desc.c files rely on.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/* ugly hack, same as in e.g pg_controldata */
+#define FRONTEND 1
+#include "postgres.h"
+
+#include "catalog/catalog.h"
+#include "datatype/timestamp.h"
+#include "lib/stringinfo.h"
+#include "storage/relfilenode.h"
+#include "utils/timestamp.h"
+#include "utils/datetime.h"
+
+const char *
+timestamptz_to_str(TimestampTz dt)
+{
+    return "unimplemented-timestamp";
+}
+
+const char *
+relpathbackend(RelFileNode rnode, BackendId backend, ForkNumber forknum)
+{
+    return "unimplemented-relpathbackend";
+}
+
+/*
+ * Provide a hacked up compat layer for StringInfos so xlog desc functions can
+ * be linked/called.
+ */
+void
+appendStringInfo(StringInfo str, const char *fmt, ...)
+{
+    va_list        args;
+
+    va_start(args, fmt);
+    vprintf(fmt, args);
+    va_end(args);
+}
+
+void
+appendStringInfoString(StringInfo str, const char *string)
+{
+    appendStringInfo(str, "%s", string);
+}
diff --git a/contrib/pg_xlogdump/pg_xlogdump.c b/contrib/pg_xlogdump/pg_xlogdump.c
new file mode 100644
index 0000000..29ee73e
--- /dev/null
+++ b/contrib/pg_xlogdump/pg_xlogdump.c
@@ -0,0 +1,654 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_xlogdump.c - decode and display WAL
+ *
+ * Copyright (c) 2012, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *          contrib/pg_xlogdump/pg_xlogdump.c
+ *-------------------------------------------------------------------------
+ */
+
+/* ugly hack, same as in e.g pg_controldata */
+#define FRONTEND 1
+#include "postgres.h"
+
+#include <unistd.h>
+
+#include "access/xlog.h"
+#include "access/xlogreader.h"
+#include "access/rmgr.h"
+#include "access/transam.h"
+
+#include "catalog/catalog.h"
+
+#include "getopt_long.h"
+
+static const char *progname;
+
+typedef struct XLogDumpPrivateData
+{
+    TimeLineID    timeline;
+    char       *inpath;
+    XLogRecPtr    startptr;
+    XLogRecPtr    endptr;
+
+    /* display options */
+    bool        bkp_details;
+    int            stop_after_records;
+    int            already_displayed_records;
+
+    /* filter options */
+    int         filter_by_rmgr;
+    TransactionId filter_by_xid;
+} XLogDumpPrivateData;
+
+static void fatal_error(const char *fmt, ...)
+__attribute__((format(PG_PRINTF_ATTRIBUTE, 1, 2)));
+
+static void fatal_error(const char *fmt, ...)
+{
+    va_list        args;
+    fflush(stdout);
+
+    fprintf(stderr, "%s: fatal_error: ", progname);
+    va_start(args, fmt);
+    vfprintf(stderr, fmt, args);
+    va_end(args);
+    fputc('\n', stderr);
+    exit(EXIT_FAILURE);
+}
+
+/*
+ * Check whether directory exists and whether we can open it. Keep errno set
+ * error reporting by the caller.
+ */
+static bool
+verify_directory(const char *directory)
+{
+    int fd = open(directory, O_DIRECTORY|O_RDONLY);
+    if (fd < 0)
+        return false;
+    close(fd);
+    return true;
+}
+
+static void
+split_path(const char *path, char **dir, char **fname)
+{
+    char *sep;
+
+    /* split filepath into directory & filename */
+    sep = strrchr(path, '/');
+
+    /* directory path */
+    if (sep != NULL)
+    {
+        /* windows doesn't have strndup */
+        *dir = strdup(path);
+        (*dir)[(sep - path) + 1] = '\0';
+        *fname = strdup(sep + 1);
+        }
+    /* local directory */
+    else
+    {
+        *dir = NULL;
+        *fname = strdup(path);
+    }
+}
+
+/*
+ * Try to find the file in several places:
+ * if directory == NULL:
+ *   fname
+ *   XLOGDIR / fname
+ *   $PGDATA / XLOGDIR / fname
+ * else
+ *   directory / fname
+ *   directory / XLOGDIR / fname
+ *
+ * return a read only fd
+ */
+static int
+fuzzy_open_file(const char *directory, const char *fname)
+{
+    int fd = -1;
+    char fpath[MAXPGPATH];
+
+    if (directory == NULL)
+    {
+        const char* datadir;
+
+        /* fname */
+        fd = open(fname, O_RDONLY | PG_BINARY, 0);
+        if (fd < 0 && errno != ENOENT)
+            return -1;
+        else if (fd > 0)
+            return fd;
+
+        /* XLOGDIR / fname */
+        snprintf(fpath, MAXPGPATH, "%s/%s",
+                 XLOGDIR, fname);
+        fd = open(fpath, O_RDONLY | PG_BINARY, 0);
+        if (fd < 0 && errno != ENOENT)
+            return -1;
+        else if (fd > 0)
+            return fd;
+
+        datadir = getenv("PGDATA");
+        /* $PGDATA / XLOGDIR / fname */
+        if (datadir != NULL)
+        {
+            snprintf(fpath, MAXPGPATH, "%s/%s/%s",
+                     datadir, XLOGDIR, fname);
+            fd = open(fpath, O_RDONLY | PG_BINARY, 0);
+            if (fd < 0 && errno != ENOENT)
+                return -1;
+            else if (fd > 0)
+                return fd;
+        }
+    }
+    else
+    {
+        /* directory / fname */
+        snprintf(fpath, MAXPGPATH, "%s/%s",
+                 directory, fname);
+        fd = open(fpath, O_RDONLY | PG_BINARY, 0);
+        if (fd < 0 && errno != ENOENT)
+            return -1;
+        else if (fd > 0)
+            return fd;
+
+        /* directory / XLOGDIR / fname */
+        snprintf(fpath, MAXPGPATH, "%s/%s/%s",
+                 directory, XLOGDIR, fname);
+        fd = open(fpath, O_RDONLY | PG_BINARY, 0);
+        if (fd < 0 && errno != ENOENT)
+            return -1;
+        else if (fd > 0)
+            return fd;
+    }
+    return -1;
+}
+
+/* this should probably be put in a general implementation */
+static void
+XLogDumpXLogRead(const char *directory, TimeLineID timeline_id,
+                 XLogRecPtr startptr, char *buf, Size count)
+{
+    char       *p;
+    XLogRecPtr    recptr;
+    Size        nbytes;
+
+    static int    sendFile = -1;
+    static XLogSegNo sendSegNo = 0;
+    static uint32 sendOff = 0;
+
+    p = buf;
+    recptr = startptr;
+    nbytes = count;
+
+    while (nbytes > 0)
+    {
+        uint32        startoff;
+        int            segbytes;
+        int            readbytes;
+
+        startoff = recptr % XLogSegSize;
+
+        if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo))
+        {
+            char        fname[MAXFNAMELEN];
+
+            /* Switch to another logfile segment */
+            if (sendFile >= 0)
+                close(sendFile);
+
+            XLByteToSeg(recptr, sendSegNo);
+
+            XLogFileName(fname, timeline_id, sendSegNo);
+
+            sendFile = fuzzy_open_file(directory, fname);
+
+            if (sendFile < 0)
+                fatal_error("could not find file \"%s\": %s",
+                            fname, strerror(errno));
+            sendOff = 0;
+        }
+
+        /* Need to seek in the file? */
+        if (sendOff != startoff)
+        {
+            if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0)
+            {
+                int        err = errno;
+                char    fname[MAXPGPATH];
+                XLogFileName(fname, timeline_id, sendSegNo);
+
+                fatal_error("could not seek in log segment %s to offset %u: %s",
+                            fname, startoff, strerror(err));
+            }
+            sendOff = startoff;
+        }
+
+        /* How many bytes are within this segment? */
+        if (nbytes > (XLogSegSize - startoff))
+            segbytes = XLogSegSize - startoff;
+        else
+            segbytes = nbytes;
+
+        readbytes = read(sendFile, p, segbytes);
+        if (readbytes <= 0)
+        {
+            int        err = errno;
+            char    fname[MAXPGPATH];
+            XLogFileName(fname, timeline_id, sendSegNo);
+
+            fatal_error("could not read from log segment %s, offset %d, length %d: %s",
+                        fname, sendOff, segbytes, strerror(err));
+        }
+
+        /* Update state for read */
+        recptr += readbytes;
+
+        sendOff += readbytes;
+        nbytes -= readbytes;
+        p += readbytes;
+    }
+}
+
+static int
+XLogDumpReadPage(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
+                 char *readBuff, TimeLineID *curFileTLI)
+{
+    XLogDumpPrivateData *private = state->private_data;
+    int            count = XLOG_BLCKSZ;
+
+    if (private->endptr != InvalidXLogRecPtr)
+    {
+        if (targetPagePtr + XLOG_BLCKSZ <= private->endptr)
+            count = XLOG_BLCKSZ;
+        else if (targetPagePtr + reqLen <= private->endptr)
+            count = private->endptr - targetPagePtr;
+        else
+            return -1;
+    }
+
+    XLogDumpXLogRead(private->inpath, private->timeline, targetPagePtr,
+                     readBuff, count);
+
+    return count;
+}
+
+static void
+XLogDumpDisplayRecord(XLogReaderState *state, XLogRecord *record)
+{
+    XLogDumpPrivateData *config = (XLogDumpPrivateData *) state->private_data;
+    const RmgrData *rmgr = &RmgrTable[record->xl_rmid];
+
+    if (config->filter_by_rmgr != -1 &&
+        config->filter_by_rmgr != record->xl_rmid)
+        return;
+
+    if (TransactionIdIsValid(config->filter_by_xid) &&
+        config->filter_by_xid != record->xl_xid)
+        return;
+
+    config->already_displayed_records++;
+
+    printf("xlog record: rmgr: %-11s, record_len: %6u, tot_len: %6u, tx: %10u, lsn: %X/%08X, prev %X/%08X, bkp:
%u%u%u%u,desc:",
 
+            rmgr->rm_name,
+            record->xl_len, record->xl_tot_len,
+            record->xl_xid,
+            (uint32) (state->ReadRecPtr >> 32), (uint32) state->ReadRecPtr,
+            (uint32) (record->xl_prev >> 32), (uint32) record->xl_prev,
+            !!(XLR_BKP_BLOCK(0) & record->xl_info),
+            !!(XLR_BKP_BLOCK(1) & record->xl_info),
+            !!(XLR_BKP_BLOCK(2) & record->xl_info),
+            !!(XLR_BKP_BLOCK(3) & record->xl_info));
+
+    /* the desc routine will printf the description directly to stdout */
+    rmgr->rm_desc(NULL, record->xl_info, XLogRecGetData(record));
+
+    putchar('\n');
+
+    if (config->bkp_details)
+    {
+        int        off;
+        char   *blk = (char *) XLogRecGetData(record) + record->xl_len;
+
+        for (off = 0; off < XLR_MAX_BKP_BLOCKS; off++)
+        {
+            BkpBlock    bkpb;
+
+            if (!(XLR_BKP_BLOCK(off) & record->xl_info))
+                continue;
+
+            memcpy(&bkpb, blk, sizeof(BkpBlock));
+            blk += sizeof(BkpBlock);
+            blk += BLCKSZ - bkpb.hole_length;
+
+            printf("\tbackup bkp #%u; rel %u/%u/%u; fork: %s; block: %u; hole: offset: %u, length: %u\n",
+                   off, bkpb.node.spcNode, bkpb.node.dbNode, bkpb.node.relNode,
+                   forkNames[bkpb.fork], bkpb.block, bkpb.hole_offset, bkpb.hole_length);
+        }
+    }
+}
+
+static void
+usage(void)
+{
+    printf("%s: reads/writes postgres transaction logs for debugging.\n\n",
+           progname);
+    printf("Usage:\n");
+    printf("  %s [OPTION] [STARTSEG [ENDSEG]] \n", progname);
+    printf("\nOptions:\n");
+    printf("  -b, --bkp-details      output detailed information about backup blocks\n");
+    printf("  -e, --end RECPTR       read wal up to RECPTR\n");
+    printf("  -h, --help             show this help, then exit\n");
+    printf("  -n, --limit RECORDS    only display n records, abort afterwards\n");
+    printf("  -p, --path PATH        from where do we want to read? cwd/pg_xlog is the default\n");
+    printf("  -r, --rmgr RMGR        only show records generated by the rmgr RMGR\n");
+    printf("  -s, --start RECPTR     read wal in directory indicated by -p starting at RECPTR\n");
+    printf("  -t, --timeline TLI     which timeline do we want to read, defaults to 1\n");
+    printf("  -V, --version          output version information, then exit\n");
+    printf("  -x, --xid XID          only show records with transactionid XID\n");
+}
+
+int
+main(int argc, char **argv)
+{
+    uint32        xlogid;
+    uint32        xrecoff;
+    XLogReaderState *xlogreader_state;
+    XLogDumpPrivateData private;
+    XLogRecord *record;
+    XLogRecPtr    first_record;
+    char       *errormsg;
+
+    static struct option long_options[] = {
+        {"bkp-details", no_argument, NULL, 'b'},
+        {"end", required_argument, NULL, 'e'},
+        {"help", no_argument, NULL, '?'},
+        {"limit", required_argument, NULL, 'n'},
+        {"path", required_argument, NULL, 'p'},
+        {"rmgr", required_argument, NULL, 'r'},
+        {"start", required_argument, NULL, 's'},
+        {"timeline", required_argument, NULL, 't'},
+        {"xid", required_argument, NULL, 'x'},
+        {"version", no_argument, NULL, 'V'},
+        {NULL, 0, NULL, 0}
+    };
+
+    int            option;
+    int            optindex = 0;
+
+    progname = get_progname(argv[0]);
+
+    memset(&private, 0, sizeof(XLogDumpPrivateData));
+
+    private.timeline = 1;
+    private.bkp_details = false;
+    private.startptr = InvalidXLogRecPtr;
+    private.endptr = InvalidXLogRecPtr;
+    private.stop_after_records = -1;
+    private.already_displayed_records = 0;
+    private.filter_by_rmgr = -1;
+    private.filter_by_xid = InvalidTransactionId;
+
+    if (argc <= 1)
+    {
+        fprintf(stderr, "%s: no arguments specified\n", progname);
+        goto bad_argument;
+    }
+
+    while ((option = getopt_long(argc, argv, "be:?n:p:r:s:t:Vx:",
+                                 long_options, &optindex)) != -1)
+    {
+        switch (option)
+        {
+            case 'b':
+                private.bkp_details = true;
+                break;
+            case 'e':
+                if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2)
+                {
+                    fprintf(stderr, "%s: could not parse parse --end %s\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+                private.endptr = (uint64)xlogid << 32 | xrecoff;
+                break;
+            case '?':
+                usage();
+                exit(EXIT_SUCCESS);
+                break;
+            case 'n':
+                if (sscanf(optarg, "%d", &private.stop_after_records) != 1)
+                {
+                    fprintf(stderr, "%s: could not parse parse --limit %s\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+                break;
+            case 'p':
+                private.inpath = strdup(optarg);
+                break;
+            case 'r':
+            {
+                int i;
+                for (i = 0; i < RM_MAX_ID; i++)
+                {
+                    if (strcmp(optarg, RmgrTable[i].rm_name) == 0)
+                    {
+                        private.filter_by_rmgr = i;
+                        break;
+                    }
+                }
+
+                if (private.filter_by_rmgr == -1)
+                {
+                    fprintf(stderr, "%s: --rmgr %s does not exist\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+            }
+            break;
+            case 's':
+                if (sscanf(optarg, "%X/%X", &xlogid, &xrecoff) != 2)
+                {
+                    fprintf(stderr, "%s: could not parse parse --end %s\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+                else
+                    private.startptr = (uint64)xlogid << 32 | xrecoff;
+                break;
+            case 't':
+                if (sscanf(optarg, "%d", &private.timeline) != 1)
+                {
+                    fprintf(stderr, "%s: could not parse timeline --timeline %s\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+                break;
+            case 'V':
+                puts("pg_xlogdump (PostgreSQL) " PG_VERSION);
+                exit(EXIT_SUCCESS);
+                break;
+            case 'x':
+                if (sscanf(optarg, "%u", &private.filter_by_xid) != 1)
+                {
+                    fprintf(stderr, "%s: could not parse --xid %s as a valid xid\n",
+                            progname, optarg);
+                    goto bad_argument;
+                }
+                break;
+            default:
+                goto bad_argument;
+        }
+    }
+
+    if ((optind + 2) < argc)
+    {
+        fprintf(stderr,
+                "%s: too many command-line arguments (first is \"%s\")\n",
+                progname, argv[optind + 2]);
+        goto bad_argument;
+    }
+
+    if (private.inpath != NULL)
+    {
+        /* validdate path points to directory */
+        if (!verify_directory(private.inpath))
+        {
+            fprintf(stderr,
+                    "%s: --path %s is cannot be opened: %s",
+                    progname, private.inpath, strerror(errno));
+            goto bad_argument;
+        }
+    }
+
+    /* parse files as start/end boundaries, extract path if not specified */
+    if (optind < argc)
+    {
+        char *directory = NULL;
+        char *fname = NULL;
+        int fd;
+        XLogSegNo segno;
+
+        split_path(argv[optind], &directory, &fname);
+
+        if (private.inpath == NULL && directory != NULL)
+        {
+            private.inpath = directory;
+
+            if (!verify_directory(private.inpath))
+                fatal_error("cannot open directory %s: %s",
+                            private.inpath, strerror(errno));
+        }
+
+        fd = fuzzy_open_file(private.inpath, fname);
+        if (fd < 0)
+            fatal_error("could not open file %s", fname);
+        close(fd);
+
+        /* parse position from file */
+        XLogFromFileName(fname, &private.timeline, &segno);
+
+        if (XLogRecPtrIsInvalid(private.startptr))
+            XLogSegNoOffsetToRecPtr(segno, 0, private.startptr);
+        else if (!XLByteInSeg(private.startptr, segno))
+        {
+            fprintf(stderr,
+                    "%s: --end %X/%X is not inside file \"%s\"\n",
+                    progname,
+                    (uint32)(private.startptr >> 32),
+                    (uint32)private.startptr,
+                    fname);
+            goto bad_argument;
+        }
+
+        /* no second file specified, set end position */
+        if (!(optind + 1 < argc) && XLogRecPtrIsInvalid(private.endptr))
+            XLogSegNoOffsetToRecPtr(segno + 1, 0, private.endptr);
+
+        /* parse ENDSEG if passed */
+        if (optind + 1 < argc)
+        {
+            XLogSegNo endsegno;
+
+            /* ignore directory, already have that */
+            split_path(argv[optind + 1], &directory, &fname);
+
+            fd = fuzzy_open_file(private.inpath, fname);
+            if (fd < 0)
+                fatal_error("could not open file %s", fname);
+            close(fd);
+
+            /* parse position from file */
+            XLogFromFileName(fname, &private.timeline, &endsegno);
+
+            if (endsegno < segno)
+                fatal_error("ENDSEG %s is before STARSEG %s",
+                            argv[optind + 1], argv[optind]);
+
+            if (XLogRecPtrIsInvalid(private.endptr))
+                XLogSegNoOffsetToRecPtr(endsegno + 1, 0, private.endptr);
+
+            /* set segno to endsegno for check of --end */
+            segno = endsegno;
+        }
+
+
+        if (!XLByteInSeg(private.endptr, segno) &&
+            private.endptr != (segno + 1) * XLogSegSize)
+        {
+            fprintf(stderr,
+                    "%s: --end %X/%X is not inside file \"%s\"\n",
+                    progname,
+                    (uint32)(private.endptr >> 32),
+                    (uint32)private.endptr,
+                    argv[argc -1]);
+            goto bad_argument;
+        }
+    }
+
+    /* we don't know what to print */
+    if (XLogRecPtrIsInvalid(private.startptr))
+    {
+        fprintf(stderr, "%s: no --start given in range mode.\n", progname);
+        goto bad_argument;
+    }
+
+    /* done with argument parsing, do the actual work */
+
+    /* we have everything we need, start reading */
+    xlogreader_state = XLogReaderAllocate(private.startptr,
+                                          XLogDumpReadPage,
+                                          &private);
+
+    /* first find a valid recptr to start from */
+    first_record = XLogFindNextRecord(xlogreader_state, private.startptr);
+
+    if (first_record == InvalidXLogRecPtr)
+        fatal_error("could not find a valid record after %X/%X",
+                    (uint32) (private.startptr >> 32),
+                    (uint32) private.startptr);
+
+    /*
+     * Display a message that were skipping data if `from` wasn't a pointer
+     * to the start of a record and also wasn't a pointer to the beginning
+     * of a segment (e.g. we were used in file mode).
+     */
+    if (first_record != private.startptr && (private.startptr % XLogSegSize) != 0)
+        printf("first record is after %X/%X, at %X/%X, skipping over %u bytes\n",
+               (uint32) (private.startptr >> 32), (uint32) private.startptr,
+               (uint32) (first_record >> 32), (uint32) first_record,
+               (uint32) (first_record - private.startptr));
+
+    while ((record = XLogReadRecord(xlogreader_state, first_record, &errormsg)))
+    {
+        /* continue after the last record */
+        first_record = InvalidXLogRecPtr;
+        XLogDumpDisplayRecord(xlogreader_state, record);
+
+        /* check whether we printed enough */
+        if (private.stop_after_records > 0 &&
+            private.already_displayed_records >= private.stop_after_records)
+            break;
+    }
+
+    if (errormsg)
+        fatal_error("error in WAL record at %X/%X: %s\n",
+                    (uint32)(xlogreader_state->ReadRecPtr >> 32),
+                    (uint32)xlogreader_state->ReadRecPtr,
+                    errormsg);
+
+    XLogReaderFree(xlogreader_state);
+
+    return EXIT_SUCCESS;
+bad_argument:
+    fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
+    return EXIT_FAILURE;
+}
diff --git a/contrib/pg_xlogdump/tables.c b/contrib/pg_xlogdump/tables.c
new file mode 100644
index 0000000..e947e0d
--- /dev/null
+++ b/contrib/pg_xlogdump/tables.c
@@ -0,0 +1,78 @@
+/*-------------------------------------------------------------------------
+ *
+ * tables.c
+ *        Support data for xlogdump.c
+ *
+ * Portions Copyright (c) 2012, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *        contrib/pg_xlogdump/tables.c
+ *
+ * NOTES
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * rmgr.c
+ *
+ * Resource managers definition
+ *
+ * src/backend/access/transam/rmgr.c
+ */
+#include "postgres.h"
+
+#include "access/clog.h"
+#include "access/gin.h"
+#include "access/gist_private.h"
+#include "access/hash.h"
+#include "access/heapam_xlog.h"
+#include "access/multixact.h"
+#include "access/nbtree.h"
+#include "access/spgist.h"
+#include "access/xact.h"
+#include "access/xlog_internal.h"
+#include "catalog/storage_xlog.h"
+#include "commands/dbcommands.h"
+#include "commands/sequence.h"
+#include "commands/tablespace.h"
+#include "storage/standby.h"
+#include "utils/relmapper.h"
+#include "catalog/catalog.h"
+
+/*
+ * Table of fork names.
+ *
+ * needs to be synced with src/backend/catalog/catalog.c
+ */
+const char *forkNames[] = {
+    "main",                        /* MAIN_FORKNUM */
+    "fsm",                        /* FSM_FORKNUM */
+    "vm",                        /* VISIBILITYMAP_FORKNUM */
+    "init"                        /* INIT_FORKNUM */
+};
+
+/*
+ * RmgrTable linked only to functions available outside of the backend.
+ *
+ * needs to be synced with src/backend/access/transam/rmgr.c
+ */
+const RmgrData RmgrTable[RM_MAX_ID + 1] = {
+    {"XLOG", NULL, xlog_desc, NULL, NULL, NULL},
+    {"Transaction", NULL, xact_desc, NULL, NULL, NULL},
+    {"Storage", NULL, smgr_desc, NULL, NULL, NULL},
+    {"CLOG", NULL, clog_desc, NULL, NULL, NULL},
+    {"Database", NULL, dbase_desc, NULL, NULL, NULL},
+    {"Tablespace", NULL, tblspc_desc, NULL, NULL, NULL},
+    {"MultiXact", NULL, multixact_desc, NULL, NULL, NULL},
+    {"RelMap", NULL, relmap_desc, NULL, NULL, NULL},
+    {"Standby", NULL, standby_desc, NULL, NULL, NULL},
+    {"Heap2", NULL, heap2_desc, NULL, NULL, NULL},
+    {"Heap", NULL, heap_desc, NULL, NULL, NULL},
+    {"Btree", NULL, btree_desc, NULL, NULL, NULL},
+    {"Hash", NULL, hash_desc, NULL, NULL, NULL},
+    {"Gin", NULL, gin_desc, NULL, NULL, NULL},
+    {"Gist", NULL, gist_desc, NULL, NULL, NULL},
+    {"Sequence", NULL, seq_desc, NULL, NULL, NULL},
+    {"SPGist", NULL, spg_desc, NULL, NULL, NULL}
+};
diff --git a/doc/src/sgml/ref/allfiles.sgml b/doc/src/sgml/ref/allfiles.sgml
index df84054..49cb7ac 100644
--- a/doc/src/sgml/ref/allfiles.sgml
+++ b/doc/src/sgml/ref/allfiles.sgml
@@ -178,6 +178,7 @@ Complete list of usable sgml source files in this directory.<!ENTITY pgReceivexlog      SYSTEM
"pg_receivexlog.sgml"><!ENTITYpgResetxlog        SYSTEM "pg_resetxlog.sgml"><!ENTITY pgRestore          SYSTEM
"pg_restore.sgml">
+<!ENTITY pgXlogdump         SYSTEM "pg_xlogdump.sgml"><!ENTITY postgres           SYSTEM "postgres-ref.sgml"><!ENTITY
postmaster        SYSTEM "postmaster.sgml"><!ENTITY psqlRef            SYSTEM "psql-ref.sgml">
 
diff --git a/doc/src/sgml/ref/pg_xlogdump.sgml b/doc/src/sgml/ref/pg_xlogdump.sgml
new file mode 100644
index 0000000..7a27c7b
--- /dev/null
+++ b/doc/src/sgml/ref/pg_xlogdump.sgml
@@ -0,0 +1,76 @@
+<!--
+doc/src/sgml/ref/pg_xlogdump.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="APP-PGXLOGDUMP">
+ <refmeta>
+  <refentrytitle><application>pg_xlogdump</application></refentrytitle>
+  <manvolnum>1</manvolnum>
+  <refmiscinfo>Application</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>pg_xlogdump</refname>
+  <refpurpose>Display the write-ahead log of a <productname>PostgreSQL</productname> database cluster</refpurpose>
+ </refnamediv>
+
+ <indexterm zone="app-pgxlogdump">
+  <primary>pg_xlogdump</primary>
+ </indexterm>
+
+ <refsynopsisdiv>
+  <cmdsynopsis>
+   <command>pg_xlogdump</command>
+   <arg choice="opt"><option>-b</option></arg>
+   <arg choice="opt"><option>-e</option> <replaceable class="parameter">xlogrecptr</replaceable></arg>
+   <arg choice="opt"><option>-f</option> <replaceable class="parameter">filename</replaceable></arg>
+   <arg choice="opt"><option>-h</option></arg>
+   <arg choice="opt"><option>-p</option> <replaceable class="parameter">directory</replaceable></arg>
+   <arg choice="opt"><option>-s</option> <replaceable class="parameter">xlogrecptr</replaceable></arg>
+   <arg choice="opt"><option>-t</option> <replaceable class="parameter">timelineid</replaceable></arg>
+   <arg choice="opt"><option>-v</option></arg>
+  </cmdsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1 id="R1-APP-PGXLOGDUMP-1">
+  <title>Description</title>
+  <para>
+   <command>pg_xlogdump</command> display the write-ahead log (WAL) and is only
+   useful for debugging or educational purposes.
+  </para>
+
+  <para>
+   This utility can only be run by the user who installed the server, because
+   it requires read access to the data directory. It does not perform any
+   modifications.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Options</title>
+
+   <para>
+    The following command-line options control the location and format of the
+    output.
+
+    <variablelist>
+     <varlistentry>
+      <term><option>-p <replaceable class="parameter">directory</replaceable></option></term>
+      <listitem>
+       <para>
+        Directory to find xlog files in.
+       </para>
+      </listitem>
+     </varlistentry>
+    </variablelist>
+   </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Notes</title>
+  <para>
+    Can give wrong results when the server is running.
+  </para>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/reference.sgml b/doc/src/sgml/reference.sgml
index 0872168..fed1fdd 100644
--- a/doc/src/sgml/reference.sgml
+++ b/doc/src/sgml/reference.sgml
@@ -225,6 +225,7 @@   &pgDumpall;   &pgReceivexlog;   &pgRestore;
+   &pgXlogdump;   &psqlRef;   &reindexdb;   &vacuumdb;
diff --git a/src/backend/access/transam/rmgr.c b/src/backend/access/transam/rmgr.c
index cc210a7..4e94af1 100644
--- a/src/backend/access/transam/rmgr.c
+++ b/src/backend/access/transam/rmgr.c
@@ -24,6 +24,7 @@#include "storage/standby.h"#include "utils/relmapper.h"
+/* Also update contrib/pg_xlogdump/tables.c if you add something here. */const RmgrData RmgrTable[RM_MAX_ID + 1] = {
{"XLOG", xlog_redo, xlog_desc, NULL, NULL, NULL},
 
diff --git a/src/backend/catalog/catalog.c b/src/backend/catalog/catalog.c
index 6455ef0..92ab3ca 100644
--- a/src/backend/catalog/catalog.c
+++ b/src/backend/catalog/catalog.c
@@ -52,6 +52,8 @@ * If you add a new entry, remember to update the errhint below, and the * documentation for
pg_relation_size().Also keep FORKNAMECHARS above * up-to-date.
 
+ *
+ * Also update contrib/pg_xlogdump/tables.c if you add something here. */const char *forkNames[] = {    "main",
               /* MAIN_FORKNUM */
 
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index d587365..7b6ed41 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -41,7 +41,7 @@ my $contrib_extraincludes =my $contrib_extrasource = {    'cube' => [ 'cubescan.l', 'cubeparse.y' ],
 'seg'  => [ 'segscan.l',  'segparse.y' ] };
 
-my @contrib_excludes = ('pgcrypto', 'intagg', 'sepgsql');
+my @contrib_excludes = ('intagg', 'pgcrypto', 'pg_xlogdump', 'sepgsql');sub mkvcbuild{
@@ -409,6 +409,20 @@ sub mkvcbuild        'localtime.c');    $zic->AddReference($libpgport);
+    my $pgxlogdump = $solution->AddProject('pg_xlogdump', 'exe', 'contrib');
+    $pgxlogdump->{name} = 'pg_xlogdump';
+    $pgxlogdump->AddIncludeDir('src\backend');
+    $pgxlogdump->AddFiles('contrib\pg_xlogdump',
+        'compat.c', 'pg_xlogdump.c', 'tables.c');
+    $pgxlogdump->AddFile('src\backend\access\transam\xlogreader.c');
+    $pgxlogdump->AddFiles('src\backend\access\rmgrdesc',
+        'clogdesc.c', 'dbasedesc.c', 'gindesc.c', 'gistdesc.c', 'hashdesc.c',
+        'heapdesc.c', 'mxactdesc.c', 'nbtdesc.c', 'relmapdesc.c', 'seqdesc.c',
+        'smgrdesc.c', 'spgdesc.c', 'standbydesc.c', 'tblspcdesc.c',
+        'xactdesc.c', 'xlogdesc.c');
+    $pgxlogdump->AddReference($libpgport);
+    $pgxlogdump->AddDefine('FRONTEND');
+    if ($solution->{options}->{xml})    {        $contrib_extraincludes->{'pgxml'} = [
-- 
1.7.12.289.g0ce9864.dirty